Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. One example routing solution to LLN challenges is a protocol called Routing Protocol for LLNs or “RPL,” which is a distance vector routing protocol that builds a Destination Oriented Directed Acyclic Graph (DODAG, or simply DAG) in addition to a set of features to bound the control traffic, support local (and slow) repair, etc. The RPL architecture provides a flexible method by which each node performs DODAG discovery, construction, and maintenance.
LLNs are often non-synchronized systems that are based on the assumption that nodes are free to transmit (after carrier sensing) when they have data to transmit without any synchronization. One of the major issue in LLNs, especially on non-synchronized shared media links (e.g., wireless links, etc.) is link congestion: not only is the bandwidth very limited, but it is well-known that the efficiency of data transmission collapses once the offered load exceeds some known limit. Thus congestion may lead to link collapse. Current approaches generally involve increasing the bandwidth on the links close to the congestion points (e.g., at/near directed acyclic graph or “DAG” roots), such as adding links, supporting multiple frequencies, etc., or performing load balancing on the traffic across a set of links across multiple (e.g., diverse) paths, among other techniques. These alternatives are directed at minimizing the risk of congestion, however there is no solution to handle the congestion once it occurs.